The present invention relates to environmentally sealed switches, and particularly to sealed switches of the snap-action type. This invention is especially directed to such switches adapted for use in a high-temperature environment, like that found in aerospace applications.
Modern aerospace vehicles, particularly jet and turboprop aircraft and rocket-powered spacecraft, require electrical switches to initiate certain automatic functions or to signal to the pilot and crew of the craft in response to movements of parts and appurtenances of the craft. For example, such a switch is used in a multi-jet-engine plane and comes into play during a braking operation. A baffle provided for each engine is moved into position to deflect the jet exhaust forwardly to help brake the plane's movement, and the switch opens and closes in response to movement of the baffle to apprise the crew of the condition of this baffle for each engine.
It is desirable that the switch be small, positive in action, and rugged, and a snap-action switch can be favorably employed to this end. Furthermore, in the above described environment, where temperatures can reach or exceed 900.degree. F., the switch construction must be reliable despite high temperatures. In addition, the switch is desirably sealed to protect its delicate internal mechanism from condensation, frost, or corrosives in the jet exhaust.
Previous sealed-snap-action switches, such as that described in U.S. Pat. No. 3,089,009, to T. Y. Korsgren, Sr., have included an actuator supported by a flexible seal in an opening of the switch's casing. In such a switch extreme swings in pressure and/or temperature can affect the sensitivity of the switch, and sustained exposure to high temperatures can damage the flexible seal.